Rhodium-rich oxygen barriers

ABSTRACT

A structure and method are disclosed for forming a capacitor for an integrated circuit. The capacitor includes a rhodium-rich structure, a rhodium oxide layer in direct contact with the rhodium-rich structure, a capacitor dielectric in direct contact with the rhodium oxide layer and a top electrode over the capacitor. The rhodium-rich structure can include rhodium alloys and the capacitor dielectric preferably has a high dielectric constant.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] This invention relates to electrode structures that have good,reliable, robust contact to insulator materials having high dielectricconstants, and, in particular, to forming capacitors in microelectronicdevices with these electrode structures and high dielectric constantmaterials.

[0003] 2. Description of the Related Art

[0004] Capacitors are critical devices in integrated circuit designs,particularly for high density memory chips such as dynamic random accessmemories (DRAMs).

[0005] Capacitance is proportional to both the electrode area in contactwith the dielectric and the dielectric constant of the insulatingmaterial. As the trend toward increasing the number of devices on asingle chip has made it necessary to make devices smaller and smaller,the way in which capacitors are fabricated has had to change. Theproblem of how to increase electrode contact area without using a lot ofsurface area on the chip has been addressed by changing the topographyof capacitors. Former “flat sandwich” configurations, wherein the deviceconsists of planar layers, one on top of another, have given way to“container” and “stud” configurations, among others.

[0006] A container capacitor is made inside a hole or via in a layer ofinsulating material. The layered structure forming the capacitorconforms to the shape of the via as the layers are deposited one on topof another. Thus, the electrode contact area includes both thecylindrical side surface of the container and the circular bottom. Insome designs, the outside cylindrical surface can also be madeavailable. Yet the capacitor uses a chip surface area (“footprint”) thatis only the size of the circular top opening of the via.

[0007] Similarly, capacitors can be made in a stud configuration,wherein a column of electrode material is made through a series ofdeposition, photolithography and etch steps, and additional capacitorlayers are deposited over the column, conforming to its outer surface.Again, the surface area of the chip occupied by the capacitor is smallcompared to the total electrode/dielectric contact area, or effectivecapacitor surface area, which includes the cylindrical side surface ofthe column, as well as the top portion.

[0008] Another way to get more capacitance out of a small area is to usedielectric materials with high dielectric constants (k), so-called HDCs,such as barium strontium titanate (BST) or tantalum oxide (Ta₂O₅). Adifficulty with these materials is that they tend to lose oxygen duringhigh-temperature processing, which causes undesirable changes in theirdielectric properties and may oxidize nearby materials. Additionally,most processes for forming these materials involve highly oxidizingenvironments that can corrode conductive elements of the integratedcircuit, such as underlying polysilicon plugs.

[0009] Accordingly, there is a need for processes and materials forformation of capacitors in integrated circuits, which are compatiblewith use of high dielectric materials. It would be advantageous to use amaterial that is a barrier to oxygen diffusion from these HDC's and alsohas the electrical conductivity characteristics necessary for acapacitor electrode.

SUMMARY OF THE INVENTION

[0010] In accordance with one aspect of the invention, a capacitor isprovided within an integrated circuit. The capacitor includes arhodium-rich structure, a rhodium oxide layer in direct contact with therhodium-rich structure, a capacitor dielectric in direct contact withthe rhodium oxide layer, and a top electrode over the capacitordielectric. In the illustrated embodiments, the capacitor may have astud or container shape, may contain noble metal alloys in therhodium-rich structure and preferably employs high dielectric constantmaterials for the capacitor dielectric.

[0011] In accordance with another aspect of the invention, an electrode,consisting of a series of layers, for a semiconductor device. Theelectrode includes a first layer that includes a noble metal, and asecond layer having more than 50 atomic percent rhodium. In accordancewith another aspect of the invention, a method of fabricating anintegrated circuit. The method includes depositing a rhodium-rich layerand depositing a dielectric material thereover. The dielectric materialhas a dielectric constant greater than about 5.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] These and other aspects of the invention will be readily apparentto the skilled artisan in view of the detailed description below and theappended drawings, which are meant to illustrate and not to limit theinvention, and in which:

[0013]FIG. 1 is a schematic cross-section of a capacitor structure,constructed in accordance with the preferred embodiments.

[0014]FIG. 2 is a flow chart showing the steps for executing a preferredmethod of the present invention.

[0015]FIG. 3 is a cross-section of a stud capacitor with an exemplaryfive-layer structure, constructed according to an embodiment of thepresent invention.

[0016]FIG. 4 is a cross-sectional view of a container capacitor with afive-layer structure according to an embodiment of the presentinvention.

[0017]FIG. 5 is a schematic cross section of a stud capacitor with athree-layer structure, constructed according to an embodiment of thepresent invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0018] While illustrated in the context of high dielectric constantcapacitors, the skilled artisan will readily find application for theprinciples and advantages disclosed herein for other electricalapplications. The electrodes have particular utility adjacent volatilematerials, or when processed in highly oxidizing environments.

[0019] It is very desirable to use HDC (high dielectric constant)materials, such as barium strontium titanate (BST), tantalum oxide(Ta₂O₅). hafnium oxide (HfO₂), zirconium oxide (ZrO₂), hafnium silicate(HfO₂—SiO₂), zirconium silicate (ZrO₂—SiO₂), alumina (Al₂O₃) or niobiumoxide (Nb₂O₃), in capacitors for integrated circuits, as they providegreater capacitance density than do materials with lower dielectricconstants and, thus, yield a greater capacitance for a smaller surfacearea. Unfortunately, these materials tend to lose oxygen duringsubsequent high-temperature processing, which can result in leakagecurrent through the capacitor and in oxidation of surrounding materialsduring deposition, curing and throughout the fabrication of theintegrated circuit.

[0020] Conductive electrode layers in contact with the HDC material arethe other components necessary to make a complete capacitor structure.The bottom electrode must be able to maintain good electrical contactbetween the HDC material and the substrate and to withstand highlyoxidizing environments during deposition and annealing of the HDC,typically at temperatures greater than 600 C. Some noble metals, such asplatinum, are unreactive with respect to oxygen but allow diffusion ofoxygen through them, which can lead to oxidation of nearby materials,such as the underlying contact plug and the silicon substrate.Oxidation, of course, can decrease or destroy the conductivity of theseelements.

[0021] The preferred embodiments of the current invention employ acapacitor electrode structure having a high rhodium (Rh) content, whichserves as both an oxygen diffusion barrier and a conductor. TheRh-containing layer can comprise pure Rh metal or an alloy that containsa high level of Rh. After fabrication of this electrode, which can bedone in any number of ways, as will be discussed below, theRh-containing structure makes it possible to carry out subsequenthigh-temperature process steps without degrading the HDC, withoutoxidizing surrounding materials and without losing the conductiveproperties of the electrode. The illustrated electrodes include at leasta thin interfacial layer of RhO_(x) in direct contact with thedielectric. Furthermore, rhodium oxide can form preferentially alonggrain boundaries of the Rh or Rh alloy electrode structure, thusblocking what are normally fast diffusion paths for oxygen.

[0022] With reference to FIG. 1, a capacitor 10, constructed inaccordance with the preferred embodiments is shown schematically. Thediagram is not drawn to scale. The capacitor 10 is formed over a contact12 forming a conductive path to underlying circuit components. Thiscontact 12 comprises a polysilicon plug in the preferred embodiment and,more preferably, includes a conductive diffusion barrier 14, such as athin titanium nitride layer, on its surface. The contact 12 typicallyextends through an insulating layer 16 to an active area of a transistorin a semiconductor substrate (not shown). The substrate generallycomprises the lowest level of semiconductor material in which devicesare formed. Exemplary substrates comprise single-crystal silicon wafers,epitaxial silicon layers, gallium arsenide and other III-V materiallayers.

[0023] The capacitor 10 includes a first or bottom electrode 20 thatincludes a plurality of conductive layers. At least one of the layers isrhodium-rich, i.e., contains more than about 50 atomic percent rhodium.The rhodium-rich layer preferably has greater than about 60 atomicpercent rhodium, more preferably between about 70 atomic percent and 90atomic percent rhodium.

[0024] The illustrated bottom electrode 20 includes a first orstructural conductive layer 22, which can comprise a noble metal, metalalloy, metal compound, polysilicon or a combination thereof (e.g.,titanium nitride over polysilicon). As will be appreciated from theexamples of FIGS. 3-5, the structural layer 22 can define the basicshape of the capacitor 10. The skilled artisan will readily appreciate,however, that the first layer can be omitted in favor of defining thecapacitor shape directly with the rhodium-rich structure 24.

[0025] The illustrated bottom electrode 20 shows a rhodium-richstructure 24 overlying the first conductive layer 22. The structure 24can include one or more rhodium-rich layers. Preferred examples include“pure” (>96%) rhodium; a rhodium-rich alloy, preferably with a noblemetal; and a bilayer of pure rhodium over a rhodium-rich alloy with anoble metal. Noble metals, as used herein, include ruthenium, palladium,osmium, iridium, platinum, silver and gold. Platinum is most preferredin the rhodium-rich alloy. In a bilayer, the alloy is preferablyrhodium-rich, although it will be understood that the structure 24 canbe rhodium-rich even with a small amount of rhodium in the alloy, if arelatively thick pure rhodium layer overlies the alloy.

[0026] As shown, the bottom electrode 20 also includes a rhodium oxide(RhO_(x)) layer 26 formed directly over the rhodium-rich structure 24.As will be appreciated from the discussion of FIG. 2 below, the rhodiumoxide layer 26 can comprise a thin interfacial layer, formed naturallyduring high k dielectric deposition and curing, but more preferablycomprises a deposited or grown layer. More preferably, the rhodium oxidelayer 26 comprises stoichiometric Rh₂O₃.

[0027] The illustrated dielectric layer 30 is a material with a highdielectric constant, k. High dielectric constant materials, known asHDCs, as used herein, include materials whose dielectric constant isgreater than 5, more preferably greater than 10 and most preferablygreater than 20. Preferred materials that meet these criteria includebarium strontium titanate (BST), tantalum oxide (Ta₂O₅), hafnium oxide(HfO₂), zirconium oxide (ZrO₂), hafnium silicate (HfO₂—SiO₂), zirconiumsilicate (ZrO₂—SiO₂), alumina (Al₂O₃) and niobium oxide (Nb₂O₃).

[0028] The capacitor 10 includes a second or top electrode 40 that alsocomprises a plurality of conductive layers. The rhodium oxide layer(RhO_(x)) 42 is analogous to the RhO_(x) layer 26 in the bottomelectrode 20. This top electrode RhO_(x) layer 42 can be formed as athin interfacial layer, when curing of the HDC layer is done subsequentto deposition of the rhodium-rich layer 44 or during other subsequentheat treatments of the integrated circuit.

[0029] In another arrangement, the RhO_(x) layer 42 is formed bydeposition of a thin film of pure rhodium, and then oxidizing it fully.More preferably, the RhO_(x) layer 42 is deposited directly onto the HDClayer by chemical vapor deposition. Most preferably, the resulting oxidecomprises stoichiometric Rh₂O₃.

[0030] Overlying the RhO_(x) layer in the illustrated top electrode is arhodium-rich structure 44, analogous to the rhodium-rich structure 24 inthe bottom electrode. The structure 44 can include one or morerhodium-rich layers. As described for structure 24 above, preferredexamples include “pure” (>96%) rhodium; a rhodium-rich alloy, preferablywith a noble metal; and a bilayer of pure rhodium over a rhodium-richnoble metal alloy. Again, platinum is most preferred in the rhodium-richalloy. As is known in the art, the top electrode can then be patterned,either for each individual cell or for each array.

[0031] The capacitor is fabricated according to the method outlined inthe flow chart of FIG. 2. The desired capacitor shape can be formed 200in any of a number of configurations, preferably, as noted in thediscussion of FIG. 1, by shaping the structural layer 22. Variouspossibilities include flat sandwich structures, wherein the deviceconsists of planar layers as shown in FIG. 1, folding stacked or trenchstructures and structures with rugged surfaces. These examples are meanthere to aid in illustrating embodiments of the invention and not toexclude other configurations that may be used by one of ordinary skillin the art.

[0032] Preferred embodiments for capacitor shape include container andstud structures. A container structure is fabricated inside a hole thathas been formed in a layer of insulating material. For example, thestructural conductive layer 22, shown in FIG. 1, can be deposited toconform to the shape of the hole, and the other structures comprisingthe capacitor are formed over this layer within the hole, as will bediscussed below. A stud structure obtains when structural layer 22 formsa column of material, and subsequent capacitor structures are formedover this column. The skilled artisan will be familiar with theprocedure involved in forming these initial hole and column structures,which include deposition, photolithography and etch steps.

[0033] With continuing reference to FIG. 2, a rhodium-rich structure isdeposited over and conforms with the capacitor shape 220. In thepreferred embodiment, the structure is formed by chemical vapordeposition (CVD), more preferably metal organic chemical vapordeposition (MOCVD). As discussed above in reference to FIG. 1, therhodium-rich structure can include one or more rhodium-rich layers andthat the term rhodium-rich can mean pure rhodium, i.e., more than 96atomic percent rhodium, or a rhodium-rich noble metal alloy, wherein therhodium content is at least 50 atomic percent, preferably greater than60 atomic percent, and, more preferably between 70 atomic percent and 90atomic percent.

[0034] The precursor gas used to form the pure Rh layer by CVD or MOCVDcan be chosen from a number of volative rhodium compounds, includingRh₂(μ-Cl)₂(CO)₄, Rh(η⁵-C₅H₅)(CO)₂, Rh(η⁵-C₅H₅)(1.5-COD),Rh(η³-allyl)(CO)₂, Rh(η³-allyl)₃ and ((PF₃)₂RhCl₂)₂. Other known andyet-to-be developed volatile rhodium compounds can also be employed. Inthe preferred embodiment, Rh(η⁵-C₅H₅)(CO)₂ is used. The depositiontemperature is preferably between about 200 C. and 550 C., morepreferably, between 250 C. and 500 C. Preferred carrier gases are heliumand argon. Those skilled in the art will understand that depositionconditions must be optimized for each precursor gas throughexperimentation. Although films deposited under vacuum with organicsource gases may be significantly contaminated with carbon and oxygen,when the precursor gas is combined with hydrogen, the purity of thedeposited rhodium film can be greater than 90%, and even as high as 98%.

[0035] When a rhodium-rich alloy is deposited by MOCVD in anotherarrangement, the gases used to form the layer are a combination of thegases that form the pure elements. The rhodium-rich alloy that is mostpreferred is Rh—Pt. An exemplary precursor gas for platinum ismethyl-cyclopendadienylplatinum(IV)-trimethyl (MeCpPt(Me)₃). This gas iscombined with a rhodium precursor gas in a proportion to produce thedesired alloy composition in the deposited film. The flow rate of the Rhprecursor gas is preferably between about 15 sccm and 100 sccm. For thePt precursor gas, the flow rate is preferably between about 5 sccm and200 sccm. The pressure in the deposition chamber is between about 1 Torrand 80 Torr. The MOCVD temperature for Rh—Pt is between 300 C. and 500C., more preferably, between 350 C. and 460 C. A preferred oxidizing gasis nitrous oxide (N₂O) with a flow rate of between about 100 sccm and1500 sccm. Other oxidizing gases, such as NO, O₂, O₃ or H₂O can also beused at flow rates between about 100 sccm and 1500 sccm.

[0036] Rhodium oxide is formed 230 directly over the rhodium-richstructure. In one embodiment, RhO_(x) is formed by oxidizing a portionof the rhodium-rich layer. The oxidation is performed in anoxygen-containing atmosphere, such as O, O₂, NO, N₂O or H₂O and at atemperature preferably between about 300C to 800 C, more preferably,between about 400 C. and 700 C. The pressure in the chamber is betweenabout 1 Torr and 660 Torr, and oxidation proceeds for between about 0.5min and 3.0 min.

[0037] In another arrangement, the rhodium oxide structure can be formeddirectly by chemical vapor deposition, preferably using the precursorgas Rh(η⁵-C₅H₅)(CO)₂ with a flow rate of between about 10 sccm and 100sccm, an oxidizing agent (e.g., N₂O) at between 50 sccm and 1500 sccm,and a pressure of between about 1 Torr and 80 Torr. The depositiontemperature is between 200 C. and 550 C. and, more preferably, between300 C. and 500 C. In the preferred embodiment, the film is subsequentlyannealed at preferably between about 350 C. and 460 C., for about 0.5minutes to 2.0 minutes to increase the grain size and reduce the carboncontent of the film.

[0038] Even in the absence of a positive step of formation, generallysome rhodium oxide will form 230 at the interface during subsequentdeposition and annealing 240, of a high k dielectric layer (HDC) overthe rhodium-rich structure.

[0039] The HDC layer can be formed of any material with a highdielectric constant, but preferably comprises barium strontium titanate.Generally barium strontium titanate (BST) can be formed with volatilereactants containing barium, strontium and titanium introduced into achemical vapor deposition chamber along with an oxygen ambient. Oneexemplary process uses organometallic precursors incorporatingtetramethyl heptanedionate (thd) reacted in a highly oxidizingenvironment within the process chamber. This group of exemplaryprecursors comprises Ba(thd)₂ and Sr(thd)₂ with eitherTi(isoproproxy)₂(thd)₂ or Ti(O-i-Pr)₂(thd)₂. Preferably the chemicalvapor deposition occurs in a temperature range of about 500 C. to 800C., more preferably, 600 C. to 700 C. Another exemplary process usesprecursors comprising Ba(DPM)₂(tet), Sr(DPM)₂(tet) and Ti(O-i-C₃H₇)₄where DPM is bis(dipivaloylmethanato) and tet is tetraglyme. Preferablythis deposition occurs in a temperature range of about 400 C. to about700 C. The BST layer is annealed subsequently at between 400 C. and 650C., more preferably at about 550 C., in an oxygen-containing atmosphere.An exemplary annealing atmosphere includes a mixture of O₂ and N₂O at apressure of between 50 Torr and 660 Torr, more preferably at about 660Torr.

[0040] Alternatively, tantalum oxide (Ta₂O₅) can serve as the HDC layer.Tantalum oxide can be deposited by chemical vapor deposition usingTa(OC₂H₅)₅ gas carried by helium gas at a temperature between about 350C. and 550 C., more preferably between about 430 C. and 500 C. The flowrate of the oxygen gas is between about 100 sccm and 1500 sccm, and thechamber pressure is between about 1 Torr and 20 Torr. The Ta₂O₅ isannealed at 400 C. to 500 C. in ultraviolet light for between about 30seconds and 10 minutes, preferably, about 3 minutes, in an O₂ or O₃atmosphere. Alternatively, the Ta₂O₅ layer can be annealed at 700 C. to850 C., preferably about 750 C., for 10 minutes to 2 hours, morepreferably about 1 hour, in an oxygen or steam atmosphere.

[0041] Following HDC deposition 240, an upper rhodium oxide ispreferably formed 250 directly over the HDC layer. In one embodiment,the rhodium oxide structure can be formed directly by chemical vapordeposition, as was discussed above for step 230. Alternatively, a layerof Rh metal having a thickness between about 1 nm and 10 nm, morepreferably between about 2 nm and 5 nm, is deposited onto the HDC layer.This layer is then oxidized completely, as was described as onepossibility for the first rhodium oxide formation 230. The finishedoxide layer has a thickness about two times that of the initial rhodiummetal layer.

[0042] An upper rhodium-rich structure is deposited 260 over the rhodiumoxide. This deposition 260 can employ the same methods discussed earlierfor step 220.

[0043] Exemplary structures fabricated according to preferredembodiments of the current invention, are illustrated in FIGS. 3-5.

[0044] An exemplary stud capacitor can be understood with reference toFIG. 3, not drawn to scale. A portion of a silicon substrate 100 isshown with an insulating overlayer 112. There is a contact hole in theinsulating layer 112 that is filled with polysilicon 114 and overlaidwith a thin titanium nitride (TiN) or titanium silicon nitride(TiSi_(x)N_(y)) diffusion barrier layer 116. Preferably the thickness ofthe diffusion barrier layer is between about 40 nm and 200 nm. Thecapacitor structure is formed with an initial column of Pt 118, followedby a layer of Rh-rich Rh-Pt alloy 120, a layer of HDC 122, anotherRh-rich Rh-Pt alloy layer 124, and finally another Pt layer 126. Thediameter of the Pt column 118 is preferably between about 50 nm and 1000nm, more preferably between about 50 nm and 500 nm. The thickness ofeach Rh-rich layer 120, 124 is preferably between about 20 nm and 100nm, more preferably between 20 nm and 50 nm. The thickness of the HDClayer 122 is preferably between about 8 nm and 40 nm for BST and betweenabout 3 nm and 20 nm for Ta₂O₅. The Pt layer 126 has a thickness ofbetween about 10 nm and 100 nm, more preferably between about 20 nm and50 nm.

[0045] Similarly, an exemplary container capacitor is illustrated inFIG. 4, not drawn to scale. Again, there is a silicon substrate 100 anda polysilicon plug 114 covered with a diffusion barrier layer 116. Theplug 114 is formed in a contact hole in an insulating layer 112. Acontainer hole has been formed in a thick insulating layer 130. Thediameter of the container hole is preferably between about 50 nm and1000 nm, more preferably between about 50 nm and 500 nm for astate-of-the art DRAM circuit design. The capacitor structure is formedwith a Rh layer 132 conforming to the shape of the container. Thethickness of the Rh layer 132 is preferably between about 20 nm and 100nm, more preferably between about 20 nm and 50 nm. This is covered withRhO_(x) 134, a layer of HDC 136 and another RhO_(x) layer 138. Thethickness of each RhO_(x) layer is preferably between about 1.0 nm and20.0 nm, more preferably between about 5.0 nm and 10.0 nm. The thicknessof the HDC layer 136 is preferably between about 10 nm and 40 nm for BSTand between about 3 nm and 20 nm for Ta₂O₅. The remaining opening isfilled with Rh 140.

[0046] Another exemplary stud capacitor is shown in FIG. 5, not drawn toscale. The underlying structures are as described above for FIGS. 3 and4. The capacitor structure includes a bottom electrode of Rh 150 in theshape of a stud that is covered with an HDC layer 152, and then with alayer of Rh comprising the top electrode 154. The diameter of the studis preferably between about 50 nm and 1000 nm, more preferably betweenabout 50 nm and 500 nm. The thickness of the HDC layer 152 is preferablybetween about 10 nm and 40 nm for BST and between about 3 nm and 20 nmfor Ta₂O₅. The top layer of Rh is preferably between about 20 nm and 100nm, more preferably between about 20 nm and 50 nm. A thin interfaciallayer of rhodium oxide forms at the boundaries of the Rh layers 150, 154and HDC layer 152.

[0047] Advantageously, the preferred embodiments provide processes andmaterials that are compatible with use of high dielectric materials forfabrication of capacitors in integrated circuits. Rhodium is very usefulas an electrode, particularly adjacent to HDC's. Rhodium is also a goodoxygen diffusion barrier and thus prevents out diffusion of oxygen fromthe HDC, thereby protecting nearby materials in the integrated circuitfrom the detrimental effects of oxidation. Additionally, loss of oxygenfrom HDC materials causes undesirable changes in their dielectricproperties. Because oxygen cannot diffuse out, it is trapped inside theHDC layer, thereby preserving its dielectric properties.

[0048] Much of the processing to form these structures involves highlyoxidizing environments, and there is some oxidation of rhodium at theHDC/Rh interface. But as both rhodium and rhodium oxide have goodelectrical conductivity, the electrodes remain conductive. Rhodium oxideat the interface between rhodium rich structures and HDCs also serves asa diffusion barrier. Capacitors formed with HDC materials and rhodiumtend not to degrade over time.

[0049] In the prior art, ruthenium oxide (RuO_(x)) has been used as anelectrode material, but it is a strong oxidizer, and it tends to oxidizethe surrounding materials. Platinum has also been used. Platinum doesnot oxidize, but does not form an effective barrier to oxygen diffusion.Thus, oxygen can diffuse through platinum and react with surroundingmaterials. Electrodes containing a high rhodium content can overcomethere problems.

[0050] Although the foregoing invention has been described in terms ofcertain preferred embodiments, other embodiments will become apparent tothose of ordinary skill in the art, in view of the disclosure herein.For example, while the preferred embodiments describe stud and containerconfigurations, the skilled artisan will find application for theprinciples disclosed herein to more simple or more complex capacitordesigns. Accordingly, the present invention is not intended to belimited by the recitation of preferred embodiments, but is intended tobe defined solely by reference to the appended claims.

What is claimed is:
 1. A capacitor within an integrated circuitcomprising: a rhodium-rich structure; a rhodium oxide layer in directcontact with the rhodium-rich structure; a capacitor dielectric indirect contact with the rhodium oxide layer; and a top electrode overthe capacitor dielectric.
 2. The capacitor of claim 1, wherein the topelectrode comprises a second rhodium-rich structure.
 3. The capacitor ofclaim 2, wherein the top electrode comprises a pure rhodium layer. 4.The capacitor of claim 2, wherein the second rhodium-rich structurecomprises a noble metal alloy layer.
 5. The capacitor of claim 4,wherein the noble metal alloy layer comprises a Rh-Pt alloy containingmore than about 50 atomic percent Rh.
 6. The capacitor of claim 2,wherein the top electrode comprises a second rhodium oxide layer betweenthe dielectric and the second rhodium-rich structure of the topelectrode.
 7. The capacitor of claim 6, wherein each of the rhodiumoxide layers is 1 nm to 20 nm thick.
 8. The capacitor of claim 2,wherein each of the rhodium-rich structures is between 20 nm and 100 nmthick.
 9. The capacitor of claim 1, wherein the capacitor is formed in acontainer shape.
 10. The capacitor of claim 1, wherein the capacitor isformed in a stud shape.
 11. The capacitor of claim 1, wherein thecapacitor dielectric comprises a material having a dielectric constantgreater than about
 5. 12. The capacitor of claim 1, wherein thecapacitor dielectric comprises a material having a dielectric constantgreater than about
 10. 13. The capacitor of claim 1, wherein thecapacitor dielectric comprises a material having a dielectric constantgreater than about
 20. 14. The capacitor of claim 1, wherein thecapacitor dielectric comprises barium strontium titanate (BST).
 15. Thecapacitor of claim 14, wherein the BST thickness is between 8 nm and 40nm.
 16. The capacitor of claim 1, wherein the capacitor dielectriccomprises tantalum oxide (Ta₂O_(x)).
 17. The capacitor of claim 16,wherein the Ta₂O₅ thickness is between 3 nm and 20 nm.
 18. An electrodefor a semiconductor device consisting of a series of layers comprising:a first layer comprising a noble metal; and a second layer containingmore than 50 atomic percent rhodium.
 19. The electrode of claim 18,wherein the thickness of the first layer is between 20 nm and 100 nm.20. The electrode of claim 18, wherein the first layer comprises Pt. 21.The electrode of claim 20, wherein the first layer further comprises Rh.22. The electrode of claim 21, wherein the layer comprising Rh consistsof Rh-Pt alloys containing at least 70% Rh.
 23. An integrated circuitcapacitor comprising: a dielectric layer having a dielectric constantgreater than about 5; and electrodes in contact with the dielectriclayer, the electrodes comprising rhodium-rich structures.
 24. Thecapacitor of claim 23, formed in electrical contact with an underlyingsemiconductor substrate through a polysilicon plug.
 25. A method offabricating an integrated circuit comprising: depositing a rhodium-richlayer; and depositing a material having a dielectric constant greaterthan about 5 over the rhodium-rich layer.
 26. The method of claim 25,further comprising depositing a second rhodium-rich layer over thedielectric.
 27. The method of claim 26, wherein each of the rhodium-richlayers includes an alloy of Rh with another noble metal.
 28. The methodof claim 26, wherein each of the rhodium-rich layers is greater thanabout 96% Rh.
 29. The method of claim 25, further comprising depositingRhO_(x) directly over the rhodium-rich layer prior to depositing thedielectric layer.
 30. The method of claim 25, further comprisingdepositing RhO_(x) directly over the dielectric prior to depositing theRh-rich layer.
 31. A method of fabricating a capacitor for an integratedcircuit comprising: forming a desired capacitor shape; forming arhodium-rich structure to conform to the capacitor shape; formingrhodium oxide directly over the rhodium-rich structure; depositing alayer of dielectric material with a high dielectric constant (HDC)directly over the rhodium oxide; forming rhodium oxide directly over theHDC; and forming a rhodium-rich structure.
 32. The method of claim 31,wherein the rhodium-rich structures are greater than about 96% Rh. 33.The method of claim 31, wherein forming the rhodium-rich structurescomprises chemical vapor deposition.
 34. The method of claim 33, whereinforming the rhodium-rich structures comprises metal organic chemicalvapor deposition (MOCVD).
 35. The method of claim 34, wherein theprecursor gases used in the MOCVD are Rh(η⁵-C₅H₅)(CO)₂ and N₂O.
 36. Themethod of claim 35, wherein the deposition temperature is between 200 C.and 550 C.
 37. The method of claim 31, wherein the rhodium-richstructures comprise an alloy of Rh with another noble metal.
 38. Themethod of claim 31, wherein forming rhodium oxide directly over therhodium-rich structure comprises oxidizing a top portion of therhodium-rich structure.
 39. The method of claim 31, wherein forming therhodium oxide directly over the HDC comprises first depositing a thinlayer of Rh metal and oxidizing the entire Rh layer.
 40. The method ofclaim 39, wherein the oxidizing comprises exposing the Rh layer to anoxygen-containing atmosphere selected from a group that consists of O,O₂, NO, N₂O and H₂O.
 41. The method of claim 40, wherein the oxidationis performed at a temperature of 300C to 800 C.
 42. The method of claim31, wherein forming rhodium oxide comprises chemical vapor deposition.43. The method of claim 42, wherein Rh(η⁵-C₅H₅)(CO)₂ gas is used in thechemical vapor deposition.
 44. The method of claim 43, wherein thechemical vapor deposition is performed between 200C and 550 C.
 45. Themethod of claim 31, wherein depositing a layer of dielectric materialcomprises chemical vapor deposition of barium strontium titanate (BST)using precursors Ba(DPM)₂(tet), Sr(DPM)₂(tet) and Ti(O-i-C₃H₇)₄, whereDPM is bis(dipivaloylmethanato) and tet is tetraglyme.
 46. The method ofclaim 45, wherein the chemical vapor deposition is performed at betweenabout 400 C. and 700 C., and the BST is subsequently annealed at between400 C. and 650 C. in an oxygen atmosphere.
 47. The method of claim 31,wherein depositing a layer of dielectric material comprises chemicalvapor deposition of barium strontium titanate (BST) using precursorsBa(thd)₂ and Sr(thd)₂ with either Ti(isoproproxy)₂(thd)₂ orTi(O-i-Pr)₂(thd)₂, where thd is tetramethyl heptanedionate.
 48. Themethod of claim 47, wherein the chemical vapor deposition is performedat between about 500 C. to 800 C., and the BST is subsequently annealedat between 400 C. and 650 C. in an oxygen atmosphere.
 49. The method ofclaim 31, wherein depositing a layer of dielectric material comprises rfmagnetron sputtering a Ba₀ ₅Sr₀ ₅TiO₃ target in a mixture of Ar and O₂to form barium strontium titanate (BST).
 50. The method of claim 49,further comprising annealing the BST in an N₂ ambient for about 1 minuteusing a rapid thermal processor (RTP).
 51. The method of claim 31,wherein depositing a layer of dielectric material comprises chemicalvapor deposition to form tantalum oxide (TaO_(x)) using Ta(OC₂H₅)₅ gascarried by helium.
 52. The method of claim 51, wherein the chemicalvapor deposition is performed at between 350 C. and 550 C.
 53. Themethod of claim 52, further comprising annealing the TaO_(x) at 400C.-500 C. in uv light for 30 secs to 10 minutes in an O₂ or O₃atmosphere.
 54. The method of claim 52, further comprising annealing theTaO_(x) at 700 C.-850 C. for 10 minutes to 2 hours in an oxygen or steamatmosphere.